The invention relates to an optical scanning device for scanning an information track of an optically scannable information carrier, which scanning device includes a radiation source, an optical lens system with an optical axis for focusing a radiation beam supplied, in operation, by the radiation source into a scanning spot on the information carrier, and a first actuator for moving the lens system parallel to the optical axis, the lens system being provided with a main lens, an auxiliary lens, and a second actuator for moving the main lens and the auxiliary lens relative to each other.
The invention further relates to an optical lens system which can suitably be used in an optical scanning device in accordance with the invention.
The invention also relates to an optical player including a table which can be rotated about an axis of rotation, an optical scanning device for scanning an information track of an optically scannable information carrier which can be placed on the table, and a displacement device by means of which the scanning device can be moved, in operation, mainly in a radial direction relative to the axis of rotation.
An optical scanning device and an optical player of the types mentioned in the opening paragraphs are known from U.S. Pat. No. 5,712,842. The main lens of the optical lens system of the known optical scanning device is an objective lens, while the auxiliary lens is a relatively small, so-called solid immersion lens which is arranged between the objective lens and the information carrier to be scanned. By using the auxiliary lens, the lens system of the known scanning device has a relatively large numerical aperture, so that a relatively small scanning spot on the information carrier to be scanned is obtained. By virtue thereof, the known scanning device can suitably be used to scan information carriers having relatively small elementary information characteristics, that is information carriers having a relatively high information density, such as a high-density CD. By means of the first actuator of the known scanning device, the main lens and the auxiliary lens are jointly moved parallel to the optical axis, so that the scanning spot can be focused on the information layer of the information carrier. By means of the second actuator of the known scanning device, the auxiliary lens is moved relative to the main lens in a direction parallel to the optical axis, so that a spherical aberration of the radiation beam in a transparent protective layer of the information carrier present between the information layer and the scanning device can be corrected.
The above citation is hereby incorporated herein in whole by reference.